1. Field of the Invention
The invention is based on a method and an apparatus for the detection of the current distribution in a conductor of an electric machine in accordance with the preamble of patent claims 1 and 3.
2. Discussion of Background
With the preamble of patent claims 1 and 3, the invention refers to a prior art as is disclosed in the Swiss company journal: Brown Boveri Reports 5 (1978), pp. 312-317. In that case, magnetic induction changes, inter alia, are detected by means of induction coils or magnetoresistive components (field plates) for the purpose of direct contactless air gap measurement in rotating electric machines. These magnet probes are encapsulated in an elastic silicone rubber and are bonded in so-called vetresite strips.
The use of so-called Roebel bars, which are named after their inventor Ludwig Roebel and comprise a plurality of insulated conductor elements, for high-voltage windings of rotating electric machines is disclosed in the Swiss company journal: Brown Boveri Reports 2 (1980), pp. 135-140. The conductor elements are transposed in such a way that every conductor element occupies every position within the bar.
Having been induced by the current displacement, eddy currents, which are confined within a solid conductor and contribute nothing to the total current, occur in stator windings of electric machines. So-called loop currents, which circulate within the parallel-connected conductor elements of Roebel bars and make no contribution to the total current of the Roebel bar, are generated in the spaces at the front and back ends of the machine by the electromagnetic field.
In order to be able to use structural countermeasures to minimize the additional current losses produced, it is desired to know the electrical current distribution within the conductor of a winding.